How to uninstall Ubuntu 12.04 after restoring Computer to factory settings?

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http://askubuntu.com – Well, firstly I reset my computer to factory settings (without knowing that Ubuntu was going to stay still). After setting up, I found out that Ubuntu was staying still at the start up boot manager, when I clicked it, it gave me errors. Ubuntu 12.04 also stole my 18GB hard drive. Now, I can’t find Ubuntu uninstaller in my programs whether I can’t find Ubuntu file in my C drive. By the way, I installed Ubuntu 12.04 with wubi installer; How do I completely remove Ubuntu from my computer? please help me with my issue, (HowTos)